Question

The focal length, f=R/2 is valid
(a) For convex mirror but not for concave mirror
(b) For concave mirror but not for convex mirror
(c) For both convex and concave mirrors
(d) Neither for convex mirror nor for concave mirror.

Answer 1

Solution:-

The Focal length is valid for both convex and concave mirrors.

Hence, Option (C) For both Convex and Concave mirrors is the correct answer .

• Focal length :- The distance between the pole and the focus is called Focal length .

• It is denoted by f

• SI unit of Focal Length is Dioptre (D).

Relationship between Focal length and Radius of Curvature are

• f = R/2

where,

f is the focal length

R is the radius of Curvature

• Radius of Curvature :- The distance between the pole and the Centre of Curvature is called the radius of Curvature.

• Pole :- The centre of the spherical mirror is called its Pole .

Answer 2

Heya !

Your answer is c.

• Focal length = R/2
• This is valid for both concave and convex mirrors.
• instead this formula for finding Focal length is applicable for the lenses as well.